A. The tradition began in the 1950s, and started slowly. According to a 2013 article in The New York Post, house lights in all Broadway theaters were first dimmed in honor of Gertrude Lawrence, who died of viral hepatitis at age 52 in September 1952 while she was starring in the Broadway musical “The King and I.” (She had gone to a hospital right after appearing in a matinee in August, The New York Times reported.) The second honoree, according to Time magazine, was Oscar Hammerstein II in 1960, for whom theater marquees briefly dimmed in a Broadway blackout the likes of which had not been seen since World War II. The third honoree, according to Playbill, was the actor Alfred Lunt in 1977.

A committee of the Broadway League, a trade association of Broadway theater owners and producers, decides who should get the honor; the marquees usually dim for one full minute at curtain time on a show night. Today, the tradition is much more common: Ruby Dee, Robin Williams, Philip Seymour Hoffman, Eli Wallach and Marian Seldes were among those honored this year, along with Ms. Rivers. Last month, the Broadway League, which had first decided not to dim the lights of its 40 theater marquees for Ms. Rivers, reversed itself after an outcry from individual theater owners and artists.